A new species of Hypsibius (Phylum Tardigrada) from Roan Mountain, Tennessee, U.S.A.

Abstract

A new tardigrade species, Hypsibius roanensis, is described from epiphytic mosses and lichens on beech trees on Roan Mountain, Tennessee. It differs from other species of the genus by the presence of a sculptured cuticle with irregular tubercles that increase in size caudally. The buccopharyngeal apparatus consists of a narrow buccal tube, well-developed apophyses, and a spherical pharynx with two granular macroplacoids. Roan Mountain is the highest cross range between the Unaka Mountains and the Blue Ridge Mountains in the Southern Appalachians. The north-facing slope of the mountain is in Carter County, Tennessee; the south-facing slope is in Mitchell County, North Carolina. Tardigrades were first recorded from Roan Mountain by Riggin (1962), who found three species of Macrobiotus at 1,890 m in Tennessee. Maucci (1987) reported 10 species in five genera (Macrobiotus, Diphascon, Minibiotus, Itaquascon, and Milnesium) from mosses collected in the spruce-fir forest of Roan Mountain above 1,829 m. The most extensive study of tardigrades on Roan Mountain was by Nelson (1973, 1975), who examined the ecological distribution of 21 species from epiphytic mosses on beech trees at approximately 1,219 m, 1,524 m, and 1,654 m on both the northand southfacing slopes. Nelson found nine specimens of a new species of Hypsibius (designated Hypsibius "a" in Nelson, 1975). However, multiple specimens from a sample were mounted per slide in a non-permanent medium (Turtox CMC9), and the slides were unsuitable for identification after 10 years. McGlothlin (1990) collected again at two of Nelson's sites to determine the long-term stability of tardigrade populations and rediscovered the new species of Hypsibius. The new species is described here. MATERIALS AND METHODS On 8 September 1988, epiphytes (primarily mosses) were collected from beech trees at approximately 1,524 m and 1,654 m on the north-facing slope of Roan Mountain, Carter County, Tennessee (Nelson's stations 5N and 6N). Fifty-six samples were collected, 27 from the 5N station and 29 from 6N. Each sample was placed in a stoppered funnel and soaked in tap water for 24 h to allow the animals to become active and then go into anoxybiosis. The epiphyte was removed and squeezed over the funnel to recover the maximal number of tardigrades. The contents of the funnel were drained into a beaker, and the top layer of water was decanted. Boiling water was added to the beaker to kill the tardigrades. Then the contents of the beaker were rinsed through two sieves, TRANS. AM. MICROSC. SOC., 112(2): 140-144. 1993. ? Copyright, 1993, by the American Microscopical Society, Inc. This content downloaded from 157.55.39.127 on Tue, 28 Jun 2016 06:58:43 UTC All use subject to http://about.jstor.org/terms VOL. 112, NO. 2, APRIL 1993 no. 18 mesh (1 mm) and no. 325 mesh (0.045 mm), simultaneously. The material remaining on the no. 325 sieve was washed into a jar with 95% ethanol. Later, the contents of the jars were examined in a gridded Petri dish under a darkfield stereomicroscope at 25 x. Tardigrades were transferred with an Irwin loop to small vials containing 95% ethanol. Up to 35 tardigrades were mounted per sample. Each specimen was removed with an Irwin loop and placed in Hoyer's mounting medium on a microscope slide and sealed with a coverslip. After the medium had dried completely, the coverslip was ringed with epoxy paint. Identifications were made using an interference phase-contrast compound microscope with oil immersion. Measurements were made with a calibrated ocular micrometer. Drawings were made with a drawing tube and photographs were taken with Kodak T Max? 100 film. The scanning electron micrograph is from Nelson's (1973) original study of Roan Mountain tardigrades.